October 19, 19996, Flushing, New York, the airplane had struck the approach
light structure and the end of the runway deck during the approach. Because
of the captain's use of monovision contact lenses, he was unable to overcome
the visual illusions resulting from the approach over water in limited
light conditions (absence of visible ground features), the irregular spacing
of the runway edge lights at shorter-than-usual intervals, the rain, and
the fog, and that these illusions led the captain to perceive that the
airplane was higher than it was during the visual portion of the approach,
and thus, to his unnecessarily steepening the approach during the final
10 seconds before impact.

Aviation medical examiners (AMEs) need to know
if pilot examinees are using contact lenses, and currently no process is
in place to ensure that AMEs are provided with that information. The lag
time in the display of vertical speed information in the vertical speed
indicator installed in the accident airplane limited the first officer's
ability to provide the captain with precise vertical speed information
during the critical final seconds of the approach, and therefore contributed
to the accident.

The probable cause was the inability of the captain, because of his
use of monovision contact lenses, to overcome his misperception of the
airplane's position relative to the runway during the visual portion of
the approach. This misperception occurred because of visual illusions produced
by the approach over water in limited light conditions, the absence of
visible ground features, the rain and fog, and the irregular spacing of
the runway lights. Contributing to the accident was the lack of instantaneous
vertical speed information available to the pilot not flying, and the incomplete
guidance available to optometrists, aviation medical examiners, and pilots
regarding the prescription of unapproved monovision contact lenses for
use by pilots.